The present invention is directed generally to electrical switches and, more specifically, to a cam follower assembly for use in push-push type latching switch assemblies.
Push-push type latching switches which control actuation of an electrical function are well known in the automotive industry. In general, push-push type latching switches could be described as switches in which the switch is normally biased to an "off" position. The switch may be pushed inwardly, and is then returned slightly rearwardly to an "on" position. The switch remains at rest in this "on" position. When one desires to turn the switch back to the "off" position the switch is again pressed inwardly, and at that time the switch returns fully to the "off" position. Various methods of achieving this movement have been utilized in the prior art.
In one recent latching assembly for latching the switch at the "on" position and allowing it to be released back to the "off" position upon release, a cam follower rides along a heart-shaped cam surface located in a latching switch assembly. The cam follower begins movement along a first face of the cam surface as the switch moves from the "off" position inwardly on a first depression of the switch. Once the switch is fully depressed, the cam follower is at the end of that first surface of the cam surface. A spring bias force then forces the cam follower into a trough, where it is retained. The cam follower secures the cam surface, and thus the switch button at this position spaced inwardly from the "off" position. This is the "on" position. In the "on" position electrical contacts associated with the switch are in a position on a circuit board where an electrical circuit is made and a vehicle function is actuated. When one desires to move the switch back to the "off" position, the switch is again depressed inwardly. The cam follower moves out of the trough and begins movement along a second surface. Eventually, the cam follower returns to its initial position.
In such prior art assemblies, the cam follower must be spring biased to a particular position relative to the housing which receives the cam follower. In the prior art, the cam follower has typically been a finger at the end of a torsion spring. The torsion spring has been mounted in the housing, and the cam follower has performed its movement along the cam surface. The torsion spring biases the cam follower as is required. However, with this type of prior art system, precise positioning and manufacture of the cam follower are required. With any variation in the mounting, positioning or manufacture of the torsion spring and cam follower, the movement of the cam follower along the cam surface will be as required for operation of the switch.
The above-described limitations in such push-push type latching switches have, heretofore, not been addressed. The invention herein solves the above-identified limitations and provides a superior latching switch assembly.